C的typedef

typedef的功用就是把某些東西變成一個預設的型態(像是int、double、char等型態)來使用
這些東西可以是enum、struct...

• 原本:

struct people{
char name[20];
int height;
int weight;
};

struct people a;

• 可以寫成

typedef struct people{
char name[20];
int height;
int weight;
}People;

People a;

• 原本

enum week{ Sun, Mon, Tue, Wed, Thu, Fri, Sat};
enum week today = Sun;

• 可以寫成
  

typedef enum week{ Sun, Mon, Tue, Wed, Thu, Fri, Sat}Week;
Week today = Sun